Please note: the default "Attach an image" button is only available for the post, pages, and attachments post types, and for default Wordpress user roles. For custom post types and custom user roles, the button is not accessible. For more advanced features, we recommend to check out the wpDiscuz Media Uploader add-on.

Well, Editor is a defult user role.

Please check here:  https://wordpress.org/documentation/article/roles-and-capabilities/#summary-of-roles

• Super Admin – somebody with access to the site network administration features and all other features. See the Create a Network article.
• Administrator (slug: ‘administrator’) – somebody who has access to all the administration features within a single site.
• Editor (slug: ‘editor’) – somebody who can publish and manage posts including the posts of other users.
• Author  (slug: ‘author’)  – somebody who can publish and manage their own posts.
• Contributor (slug: ‘contributor’) – somebody who can write and manage their own posts but cannot publish them.
• Subscriber (slug: ‘subscriber’) – somebody who can only manage their profile.

We have an intranet and some users are Editors. They can't upload images and they don't have a custom role as you can check.

Thanks!